A large section of Mt Crosby Rd - stretching from Tanderra Way in the west to Hawkesbury Rd in the east - was blocked as detectives began an investigation into what they called an "unlawful homicide."

Although the body was yet to be formally identified last night, police confirmed the deceased was wearing clothes that appeared to be similar to those worn by Mrs Baden-Clay on the night she was last seen 12 days ago.

Metropolitan North Chief Superintendent Mark Ainsworth said specialist water police, forensic officers and murder detectives were on the scene.

Asked if the body was Mrs Baden-Clay's, he answered: "I must stress that it is not a positive confirmation, however we are treating it very seriously that it is her.

"The person is subject to a recovery process and formal identification to confirm it is the missing person that we have been looking for over the last 11 days.

"The search patterns are continuing in this area and a further decision will be made about further searches of areas in the next few hours."

Mrs Baden-Clay was a 43-year-old mother of three and former Ipswich Girls Grammar School vice-head girl who graduated in 1985.

Her parents, Geoff and Priscilla Dickie, are former Ipswich residents.

Late last week they made a passionate plea for information regarding their daughter, who was reported missing from her Brookfield home by her husband Gerard about 7.30am on April 20.

Mr Baden-Clay, a Brisbane estate agent, says that he last saw his wife at home watching television about 10pm on April 19.

The spot where the body was found is not far from the quiet community of Mt Crosby, where residents were yesterday wondering what to make of the latest development.

One local business owner said there had been a lot of speculation about the find among residents.

"Personally I am surprised that something like this has happened here - it's a bit scary," she said.

"A lot of people from this area travel to Brisbane up that road. It's a pretty tight-knit community where everyone knows everyone.

"It has been a really big shock to the entire area."

Yesterday police were thick on on the ground in the area, door-knocking residents of the hills lining Kholo and Little Ugly creeks.

"There are a number of residences, particularly near the Tyarnolum Camp Site or on Bunya Street of Wirrabara Road, in the vicinity of the where the body was located," Supt Ainsworth said.

"Someone out there may have heard something that could help police with their investigations."

Police pleaded for anyone who was near the Kholo Ck bridge on the night of Thursday, April 19, who saw either a silver Holden Captiva or a white Toyota Prado, to contact them.

Supt Ainsworth said police had already received information from members of the public regarding the two vehicles as a result of the significant level of interest the story had attracted.

"At this stage we have interviewed a number of people on more than one occasion," he said.

Police refused to comment on whether or not Mrs Baden Clay's husband Gerard was a suspect.

Anyone with information that could assist police should contact Crime Stoppers on 1800 333 000.